【初学与研发之NETTY】简介与HelloWorld之例(netty3)

Netty是什么？

Netty是由JBOSS提供的一个java开源框架。Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。

特性有哪些？

1、基于灵活的、可扩展的事件驱动，API适用不同的协议（阻塞和非阻塞），支持TCP和UDP的socket服务开发。

2、高并发、低延时、高吞吐量。

3、简单、安全、可靠、易用。

如何使用？

废话不多说，请看简单的HelloWorld示例：

服务端：

package example.echo;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;

/**
* Echoes back any received data from a client.
*/
public class TestServer {

private final int port;

public TestServer(int port) {
this.port = port;
}

public void run() {
// Configure the server.
ServerBootstrap bootstrap = new ServerBootstrap(
new NioServerSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool()));

// Set up the pipeline factory.
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
public ChannelPipeline getPipeline() throws Exception {
return Channels.pipeline(new TestServerHandler());
}
});

// Bind and start to accept incoming connections.
bootstrap.bind(new InetSocketAddress(port));
}

public static void main(String[] args) throws Exception {

new TestServer(8080).run();
}
}

服务端处理Handler类：

package example.echo;

import java.nio.charset.Charset;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;

/**
* Handler implementation for the echo server.
*/
public class TestServerHandler extends SimpleChannelUpstreamHandler {

@Override
public void messageReceived(
ChannelHandlerContext ctx, MessageEvent e) {
// Send back the received message to the remote peer.
ChannelBuffer acceptBuff = (ChannelBuffer) e.getMessage();
String info = acceptBuff.toString(Charset.defaultCharset());
if(info != null && !"".equals(info)) {
System.out.println("_______服务端接收到>>>>>"+info);
ChannelBuffer sendBuff = ChannelBuffers.dynamicBuffer();
sendBuff.writeBytes("_______服务端已接收到信息！".getBytes());
e.getChannel().write(sendBuff);
} else {
e.getChannel().write("_______服务端没有接收到信息！");
}
e.getChannel().close();
}

@Override
public void exceptionCaught(
ChannelHandlerContext ctx, ExceptionEvent e) {
// Close the connection when an exception is raised.
e.getCause();
e.getChannel().close();
}
}

客户端：

package example.echo;

import java.net.InetSocketAddress;
import java.util.concurrent.Executors;

import org.jboss.netty.bootstrap.ClientBootstrap;
import org.jboss.netty.channel.ChannelFuture;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineFactory;
import org.jboss.netty.channel.Channels;
import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;

public class TestClient {

private final String host;
private final int port;
private final String firstMessageSize;

public TestClient(String host, int port, String firstMessageSize) {
this.host = host;
this.port = port;
this.firstMessageSize = firstMessageSize;
}

public void run() {
// Configure the client.
ClientBootstrap bootstrap = new ClientBootstrap(
new NioClientSocketChannelFactory(
Executors.newCachedThreadPool(),
Executors.newCachedThreadPool()));

// Set up the pipeline factory.
bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
public ChannelPipeline getPipeline() throws Exception {
return Channels.pipeline(
new TestClientHandler(firstMessageSize));
}
});

// Start the connection attempt.
ChannelFuture future = bootstrap.connect(new InetSocketAddress(host, port));

// Wait until the connection is closed or the connection attempt fails.
future.getChannel().getCloseFuture().awaitUninterruptibly();

// Shut down thread pools to exit.
bootstrap.releaseExternalResources();
}

public static void main(String[] args) throws Exception {

new TestClient("127.0.0.1", 8080, "HelloWorld, Welcome to netty！").run();
}
}

客户端处理Handler类：

package example.echo;

import java.nio.charset.Charset;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.channel.SimpleChannelUpstreamHandler;

public class TestClientHandler extends SimpleChannelUpstreamHandler {

private final String firstMessage;

/**
* Creates a client-side handler.
*/
public TestClientHandler(String firstMessageSize) {
firstMessage = firstMessageSize;
}

@Override
public void channelConnected(
ChannelHandlerContext ctx, ChannelStateEvent e) {
ChannelBuffer sendBuff = ChannelBuffers.dynamicBuffer();
sendBuff.writeBytes(firstMessage.getBytes());

e.getChannel().write(sendBuff);
System.out.println("_____客户端发送信息完成！");
}

@Override
public void messageReceived(
ChannelHandlerContext ctx, MessageEvent e) {
// Send back the received message to the remote peer.
ChannelBuffer acceptBuff = (ChannelBuffer) e.getMessage();
String info = acceptBuff.toString(Charset.defaultCharset());
System.out.println(info);
e.getChannel().close();
}

@Override
public void exceptionCaught(
ChannelHandlerContext ctx, ExceptionEvent e) {
// Close the connection when an exception is raised.
e.getCause();
e.getChannel().close();
}
}

运行服务端以及客户端后的控制台输出结果：

服务端：

_______服务端接收到>>>>>HelloWorld, Welcome to netty！

客户端：

_____客户端发送信息完成！

_______服务端已接收到信息！